Hi,

I've seen 1-2 mails on thist subject, but no real answer, so here comes
my solution for the problem. The phenomena is that the Digital
Signature Tab under Form options is gray when using a Schema as source
for a Form.
I solved it by adding following element directly under my root:

<xs:element name="Signature">
                    <xs:complexType>
                        <xs:sequence>
                            <xs:any namespace="http://www.w3.org/2000/09/xmldsig#"
processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
                        </xs:sequence>
                        <xs:anyAttribute namespace="http://www.w3.org/2000/09/xmldsig#"
processContents="lax"/>
                    </xs:complexType>
                </xs:element>
            </xs:sequence>

where xs is my schema namespace.

Have fun,
Eduard